Optical wavelength division multiplexed system using wavelength splitters

Abstract

An optical wavelength division multiplexed system uses wavelength splitters to split channels included in input light into different paths within the system. Odd-numbered channels are split into one path, and even-numbered channels are split into another path, providing increased isolation between channels. Using filters, the system then drops one or more of the isolated, split channels into paths referred to as dropped paths and allows the remaining channels to continue through the filters into output paths. The dropped paths are then combined into one, common dropped path, and the output paths are also combined into one, common output path.

1. A method of dropping channels carried in input light received by an optical wavelength divisional multiplexed system, comprising:
 splitting by the system a portion of the channels into one path within the system and another portion of the channels into another path within the system, said splitting including: 
 dividing the input light equally into two arms,  
 adding an optical phase to the divided input light which changes periodically,  
 splitting the portion of the channels into the one path and into the another path based upon the relative phase between the divided input light; and  
 
 dropping by the system one of the channels into a dropped path.  
 
   
   
     2. The method according to  claim 1 , wherein the portion of the channels includes odd-numbered channels and the another portion of the channels includes even-numbered channels. 
   
   
     3. The method according to  claim 1 , further comprising:
 outputting remaining of the channels from the system; and  
 outputting the dropped channels from the system.  
 
   
   
     4. A method of dropping channels carried in input light received by an optical wavelength division multiplexed system, comprising:
 splitting by the system the channels into at least two, separate paths within the system, said splitting including: 
 dividing the input light equally into two arms,  
 adding an optical phase to the divided input light which changes periodically,  
 splitting the channels of one of the at least two, separate paths and another of the at least two, separate paths based upon the relative phase between the divided input light; and  
 dropping by the system one of the channels into a dropped path.  
 
 
   
   
     5. A method of isolating and dropping channels carried by input light, comprising:
 splitting by a splitter the channels into separate paths, one of the paths carrying odd-numbered channels and another of the paths carrying even numbered channels, said splitting including: 
 dividing the input light equally into two arms,  
 adding an optical phase to the divided input light which changes periodically,  
 splitting the channels of one of the paths and another of the paths based upon the relative phase between the divided input light; and  
 dropping by a filter one of the channels into a dropped path.  
 
 
   
   
     6. A method of isolating a channel carried in input light received by an optical wavelength division multiplexed system, comprising:
 splitting the channel into one path and next higher and lower-numbered channels from the channel into another path, said splitting including: 
 dividing the input light equally into two arms,  
 adding an optical phase to the divided input light which changes periodically,  
 splitting the channel and the next higher and lower-numbered channels based upon the relative phase between the divided input light; and  
 
 dropping the channel into a dropped path.  
 
   
   
     7. The method according to  claim 6 , wherein the channel is odd-numbered and the next higher and lower channels are even-numbered. 
   
   
     8. The method according to  claim 6 , further comprising:
 outputting the next higher and lower channels from the system; and  
 outputting the dropped channel from the system.